New optically active polyesters derived from amino acids by replacement of the backbone amino groups for hydroxyl residues are presented. The polyesters described are the following: poly(L)HOAsp-(COOH)-OH, poly(L)HOGlu(COOH)-OH, poly(L)HOSer(OH)-OH, poly(L)HOThr(OH)-OH, poly-(L)HOLys(OH)-OH, and poly(HOAa(X)(OH)-co-LA) and some other copolymers of R-hydroxy acids. The polymers were prepared via (a) direct condensation in bulk employing several catalysts as PTSA, boric acid, Mukaiyama's reagent, stannous chloride dihydrate, (b) acyl halide activation, and (c) microwaveassisted polymerization. The obtained polymers reached a molecular weight between 1000 and 4000. The highest molecular weight attained employing polycondensation methods in solution, was either by utilizing polyacid, or metal catalyst (boric acid and stannous chloride respectively). Applying oxalyl chloride for chain extension also showed to be an efficient method. On the other hand, the microwave-assisted polymerization exhibited significant advantages and polymerization could be implemented with lack of solvent (neat). The polymers were characterized by several methods (GPC, CD, DSC, solubility), and tested for their degradability and biocompatibility to cell growth. Most of the polymers displayed a linear correlation between their calculated log P values and their experimental contact angles parameters. Transition glass temperatures (T g ) of copolymers with various compositions of LA were correlated to either Gordon Taylor equation or to a three parameters modified Kwei equation. The circular dichroism spectra (CD) of several homo and copolymers were measured. In general, CD curves of the homopolymers of HOSer, HOGlu, HOThr, HOAsp, and HOLys(OH) revealed a significant ester maxima approximately at 205-220 nm while the copolymers of HOSer with HOPhe displayed an additional cotton effect band at 200.6-201.5 nm. This is accounted for polymer rotational isomers and not to a different ππ* transition at lower wavelength.

Optically active α-hydroxy acids derived from amino acids have been synthesized and polymerized into new biodegradable polyesters. The variety of functional side chains enables the design of positively charged, negatively charged, hydrophobic and hydrophilic chiral building blocks or any combination of these constituents. Hydroxy acids of 15 natural amino acids were prepared with retention of configuration using a straightforward and reliable method of diazotization of α-amino acids. Polyesters were synthesized from these hydroxy acids by a number of methods: direct condensation in bulk, microwave assisted synthesis and ring opening polymerization. The molecular weight of the prepared polymers ranges between 2000 to 5000Da for the direct condensation and the microwave methods, whereas the ring opening polymerization results in high molecular weight polymers (20000 to 30000Da). The polymers were analyzed for their optical activity (Circular Dichroism Spectroscopy), thermal properties (DSC), solubility, molecular weight and polydispersity (GPC), and aqueous degradation. These polymers were tested for their compatibility to neuronal cells growth and differentiation.